Conventionally, in order to equalize power consumption amounts having a large difference between the daytime and the nighttime, or to compensate an output which fluctuates every moment in a natural energy power generation device, a power storage device having a secondary battery such as a sodium-sulfur battery (hereinafter, also referred to as the NaS battery) as a main component has been used.
A remaining capacity of the NaS battery can be found by loading a current value for charging and discharging in a control device such as a sequencer and adjusting and integrating it and be managed, based on an initially set remaining capacity.
However, while the NaS battery has been used over a long period of time, a difference is generated between an actual remaining capacity and a remaining capacity to be managed (hereinafter, also referred to as the remaining capacity management value). Furthermore, the difference of the remaining capacity management value varies among the NaS batteries. Therefore, the remaining capacity management value needs to be corrected or reset in order to manage the remaining capacity of the NaS battery with high accuracy.
For example, Patent Document 1 below discloses a method for correcting a remaining capacity management value in the vicinity of a charge end or in the vicinity of a discharge end.